Detectives started investigating the assault after deputies answered a call from a hospital on July 4 and took an assault report. The man, Rodolfo Rodriguez, said he was out for a walk when he was struck in the head by a concrete block. He was treated for cuts and bruises about his face and released.

Rodirguez had traveled from Mexico to see his grandson.

Investigators were ultimately led to Jones, 30.

Detectives said they are also looking for several bystanders" who took cellphone video of the attack, to aid the investigation, the L.A. County Sheriff's Department said.

Passerby Misbel Borjas told CNN she was almost hit by a block while attempting to film the attack, and heard a woman say, "go back to your country, go back to Mexico."

KTLA-TV reported investigators first thought Rodriguez may have bumped into a girl with Jones, and that was what sparked the confrontation. Rodriguez, though, said he bumped into no one.

"I just passed her and she pushed me and she hit me until she was done," Rodriguez said.